1. Field of the Invention
The present invention relates to an apparatus for the recording or reproduction of a signal on a tape-like recording medium by a rotary head, more particularly relates to an apparatus for the recording or reproduction of the signal reciprocally on a tape-like recording medium by controlling an angle of inclination of the rotary head.
2. Description of the Related Art
Known in the art is a digital video tape recorder apparatus (hereinafter referred to as a "digital VTR") which records and reproduces audio, video, and other data in the form of digital information on a magnetic tape. In such a digital VTR, to achieve both of an improvement of the frequency characteristics by an increase of the relative speed of the magnetic head and the magnetic tape and a reduction of the amount of use of the magnetic tape at the time of recording and reproduction, the data is recorded and reproduced by helical scanning, that is, using a rotary head drum on which a magnetic head are arranged and scanning the surface of the magnetic tape wound at an angle around the rotary head drum by the magnetic head.
The rotary head drum used in such a digital VTR is comprised, for example, as shown in FIG. 1, of a rotary head drum 91 on which a magnetic head 90 having a single head gap is attached and guide rollers 93 and 94 regulating the travel of the magnetic tape 92. The guide rollers 93 and 94 wind the magnetic tape 92 around the rotary head drum 91 at an angle.
As shown in for example FIG. 2, there is another rotary head drum which has two magnetic heads 95 and 96 each having a single head gap at facing positions of the rotary head drum 91. Here, the winding angle of the magnetic tape 92 is set to about a half of that in the case where one magnetic head 90 is provided on the rotary head drum 91.
In the above digital VTR, when recording data using these rotary head drums, the magnetic tape 92 is made to travel at a constant speed by a capstan servo system and the rotary head drum 91 is rotated at a constant speed by a magnetic head speed control system.
The relationship between the rotational speed of the rotary head drum and the travelling speed of the magnetic tape is determined so that, for high density recording on the magnetic tape, where one magnetic head is provided on the rotary head drum as shown in FIG. 1, one recording track having a predetermined angle of inclination is formed during one rotation of the rotary head drum and so that recording tracks are formed continuously without gaps at the predetermined angle of inclination when the rotary head drum continuously rotates. When two magnetic heads are provided on the rotary head drum as in FIG. 2, two recording tracks having the predetermined angle of inclination are formed during one rotation of the rotary head drum and recording tracks are continuously formed without gaps at the predetermined angle of inclination when the rotary head drum continuously rotates.
When the recording is carried out on the magnetic tape 92 by the magnetic head 90 or the magnetic heads 95 and 96 attached to the rotary head drum 91 in this state, as shown in FIG. 3, recording tracks 97 inclined by the amount of the predetermined angle are formed on the magnetic tape 92 without gaps.
Note that, where the above magnetic head 90 or the magnetic heads 95 and 96 has a plurality of N number of head gaps, in the configuration of FIG. 1, N number of recording tracks having the predetermined angle of inclination are formed during one rotation of the rotary head drum and recording tracks having the predetermined angle of inclination are continuously formed without gaps when the rotary head drum continuously rotates. Further, in the configuration of FIG. 2, 2N number of recording tracks having the predetermined angle of inclination are formed during one rotation of the rotary head drum and recording tracks having the predetermined angle of inclination are continuously formed without gaps when the rotary head drum continuously rotates.
In such a digital VTR, further recording and reproduction after the recording and reproduction in the FWD direction is ended requires the rewinding of the magnetic tape. For this reason, so as to perform recording again, it is necessary to first rewind all of the magnetic tape and so there is a problem that a long time is required until recording can be restarted. Particularly, handheld video cameras etc. are designed to save power, so the rewinding speed is very low and a significant time is required for the rewinding operation. Further, even if it becomes urgently necessary to record a scene, recording is impossible during this rewinding.
Here, so as to solve this problem, reciprocal recording wherein, when the recording in one direction is ended, the direction of travel of the magnetic tape is reversed and recording in the other direction is carried out can be considered.
In the above digital VTR, however, when just performing the recording by setting the direction of supply of the magnetic tape to the reverse (REV) direction without changing the rotational speed of the rotary head drum, as shown in FIG. 4, the angle of inclination of the recording track 98R formed becomes different from the angle of inclination of the recording track 98F of the forward (FWD) direction. Since the recording tracks 97 are formed in the FWD direction without gaps, the recording will be carried out while overwriting the data on the FWD direction recording tracks and therefore reciprocal recording and reproduction cannot be carried out as in an audio magnetic cassette tape.
To perform reciprocal recording by using a digital VTR, when recording in the forward (FWD) direction or the reverse (REV) direction, where one magnetic head has one head gap, it is necessary to form the recording tracks at every other track and, where one magnetic head has a plurality of N number of head gaps, it is necessary to form the recording tracks at every other N number of tracks.
In this case, first, the speed of travel of the magnetic tape 92 is made two times higher than that when the recording tracks are formed without gaps without changing the rotational speed of the rotary head drum 91 and the recording carried out making the magnetic tape travel in the FWD direction. Due to this, during the period where one or N number of recording tracks are recorded, the magnetic tape is shifted by 2 (or 2N) recording tracks and, as shown in FIG. 5A, the FWD direction recording tracks 99F are formed at every other (or every other N number) of tracks on the magnetic tape 92.
Next, when the magnetic tape is made to travel up to the end, the direction of travel of the magnetic tape is reversed to the REV direction and recording carried out while maintaining the same speed of travel for the magnetic tape. Due to this, as shown in FIG. 5B, the REV direction recording tracks 99R are formed at every other (or every other N number) of tracks.
In general, however, the angle of inclination of the rotary head drum is fixed to the angle of inclination when performing the recording in the FWD direction, so the angles of inclination of the FWD direction recording tracks 99F and the REV direction recording tracks 99R are different. For this reason, when recording in the REV direction after recording in the FWD direction, as shown in FIG. 5C, the recording is made with the REV direction recording tracks 99R partially overlapping the FWD direction recording tracks 99F on which the data was previously recorded, so there is a problem in that reciprocal recording cannot be carried out.